As a vehicle increases its speed, so too does the amount of aerodynamic drag, which in turn, increases the amount of fuel consumption required for transport. This inefficiency leads to a direct increase in operating costs. As a result, there have been many efforts to reduce aerodynamic drag, particularly on transport vehicles which are not sufficiently streamlined to minimize aerodynamic drag.
In particular, transport vehicles, such as trucks, are susceptible to aerodynamic drag, due to the shape of the cabin and/or trailer. The drag is associated both with the rear of the truck, and in the case of tractor-trailer combinations, with the space between the cabin and trailer. Often, the rear-end of a trailer is a large planar surface, which results in an area of reduced pressure to be created behind the trailer box as it travels, for example, down a highway. This in turn, generates a retarding force that must be counteracted by additional engine power.
It follows that there have been many efforts to streamline the rear of such vehicles, through the use of airfoils and other similar devices mounted at the rear of the vehicle.
U.S. Patent Application No. 20080093886 (Nussbaum) discloses a retractable air deflection apparatus for reduction of vehicular air drag, comprising at least three air deflection elements, each of which is contoured in a wing-like shape, and each of which is disposed adjacent one of the angular trailing corner edges of the vehicle. This apparatus requires a complex series of mechanical linkages.
There have been other devices that essentially comprise panels at the rear of the vehicle, which fold up onto the rear doors when not in use (see, e.g. U.S. Patent Application Nos. 20090179456; 20080309122; and 20090200834; and U.S. Pat. Nos. 6,309,010; 6,485,087; 6,666,498 and 6,799,791). These panels are fully exposed to the elements, and do not deploy in a coordinated manner. Often, manual deployment by the vehicle operator is required. Furthermore, these devices are not easily adapted for reducing the aerodynamic drag in the space between the rear of a cabin and the front surface of an attached trailer.
Breidenbach discloses in U.S. Pat. No. 7,380,868 an aerodynamic drag reducing apparatus that includes a series of successively nesting shapes and/or frameworks that extend rearward for use in a drag reducing configuration and collapse for use in a space saving configuration. The apparatus is bulky when fully deployed, and is attached to the rear doors of the vehicle. Such an apparatus cannot be easily adapted to providing drag reduction in the space between a cabin and an attached trailer. Care must be taken not to damage the apparatus when opening the rear doors to load/unload cargo. In addition, the nesting elements require a large number of complex mechanical linkages for operation.
It would be advantageous to provide a drag reducing device that is relatively simple in construction, with aerodynamic panels that deploy in a coordinated manner (either manually or automatically), for use at the rear of the vehicle and/or the space between the rear of cabin and the front of an attached trailer. When used at the rear of the vehicle, the apparatus should not couple with the rear doors of the vehicle, so as to permit easy loading/unloading of vehicular cargo. Furthermore, when not in use, the apparatus should be shielded from the elements, and also, retracted so as not to create a traffic hazard.